St. Pierre’s torn ACL marks the second time this year that a knee injury has knocked him out of a scheduled title defense. The champion was originally slated to defend his belt at UFC 137 on Oct. 29, but he was forced to withdraw from that bout after tweaking his knee in training.

Initially, St. Pierre was slated to square off with Strikeforce champion Nick Diaz at the event, but Diaz was pulled from the headlining slot after missing a pair of media appearances. Co-main event competitor Carlos Condit was instead given the shot against St. Pierre, but the champion’s injury forced officials to postpone that bout until Feb. 4.

However, after Diaz put forth a stirring performance against B.J. Penn in what became the UFC 137 main event, UFC President Dana White announced that it was Diaz, not Condit, who would receive the Super Bowl weekend shot at St. Pierre.

Following the champion’s ACL tear last week, White revealed that Diaz and Condit will lock horns at UFC 143 for an interim welterweight championship. St. Pierre expects to make a full recovery in 2012.

“I did injure my other knee, but after surgery I’ll make a full recovery in six to nine months. I’ve gotten to where I am by overcoming obstacles,” St. Pierre recently tweeted. “This will motivate me, and I make this promise to my fans: mark my words, I will be champion again. I’ll be back stronger than ever.”